Hi everyone,
I'm currently trying to control a Govee H6047 light using Bluetooth Low Energy (BLE) directly from Python (using the bleak library), without relying on the official Govee app.

I can successfully connect to the device, and I’m using the correct writable characteristic UUID:
00010203-0405-0607-0809-0a0b0c0d2b11

I’ve reverse-engineered the protocol and I'm sending 20-byte packets formatted like this:

• Starts with 0x33
• Followed by a command byte (e.g., 0x05 for color)
• Followed by the payload (e.g., RGB values)
• Zero-padded to 19 bytes
• Ends with a checksum byte (XOR of all previous bytes)

However, every time I attempt to write, I get the following error:

vbnetCopiarEditarBleakError: Could not write value [...] to characteristic ... : Unreachable 

The connection is successful
The characteristic supports write and write-without-response
Packet format and size are valid (confirmed via sniffer and other scripts)

But it still fails to write.

My hypothesis:

Newer Govee models (like the H6047, post-2022) may require an initial handshake, or some sort of session activation before accepting commands — possibly:

• A notification subscription (start_notify)
• A write to a hidden control UUID
• An initialization packet sent automatically by the app upon connection

This would explain why:

• The official app works flawlessly without internet
• But any direct BLE command from external tools fails with “Unreachable”

Questions:

• Has anyone successfully controlled the H6047 directly over BLE?
• Do you know what the app sends right after connecting?
• Can the handshake or unlock packet be captured and replayed from Python?

Thanks in advance!